Valve for rock drills



March 11, 1941. A. R. MACK 2,234,348

VALVE FOR RocKjnnILLS Filed Dec. 6, 1939 2 Sheets-Sheet 1 INVENTOR AbbepZJE-Mack HIS ATTORNEY.

March 11, 1941. A. R. MACK mm: FOR nocx mums Filed Dec. 6, me 2 Sheets-Sheet 2 HIS ATTORNEY.

Patented Mar. 11, 1941 Albert R. Mack, Phillipsburg, N. J., assignor to Ingerso'll-Rand Company,'New York, N. Y., a corporation of New Jersey Application December 6, 1939, Serial No. 307,727

7 Claims.

This invention relates to rock drills, and more particularly to a valve mechanism for effecting the distribution of pressure fluid to the percussive element of rock drills.

One object of the invention is to obtain a light weight valve mechanism of simplified construction capable of effecting a rapid distribution of pressure fluid and a consequent rapid action of the percussive element of the rock drill.

in Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings accompanying this specification and in which similar reference numerals refer to similar parts,

5 Figure 1 is a longitudinal view, partly broken away, of one form which the invention may assume in practice and showing the valve and piston elements in limiting positions,

Figure 2 is a view similar to Figure 1 showing the valve and piston elements'in other limiting positions, and

Figure 3 is a view similar to Figure 1 showing a modified form of the invention.

Referring more'particularly to the drawings, designates, in general,a rock drill comprising a cylinder 2| having a piston chamber 22 to accommodate a hammer piston 23 which is reciprocable in the piston chamber 22 and'controls I a free exhaust port 24 for the piston chamber.

The front end of the piston chamber 22 is closed by a plate 25 having a bore 26 to serve as a guide for an extension 21 of the hammer piston 23, The opposite end of the cylinder 2| is closed by a back head 28, and in the portion of the cylinder lying between the back head of the piston chamber 22 is an enlarged bore 29 to accommodate valve and rotation mechanisms designated 30 and 3|, respectively.

The valve mechanism lies immediately adjacent the rear end of the piston chamber 22 and the space of the bore 29 rearwardly ofthe valve mechanism contains the rotation mechanism which comprises the usual ratchet ring 32 wherein is arranged the head 33 of a rifle bar 34 extending through the valve mechanism and into fluted engagement with the piston 23 in a well understood manner. The head 33 of the rifle bar may be provided with a pawl or pawls 35 for engagement with the teeth 36 of the ratchet ring for holding the rifle bar stationary during a stroke of the piston 23 to cause a partial revolution thereof.

The back head 28 may be clamped to the cylin- 555 der 2| in any-well'f known manner and, .as is customary, serves as a housing for a rotary throttle valve 31 having acentral chamber 38 which may be in constant communication with a source of pressure fluid supply, and in the wall of the throttle valve is a port 39 to afford communica- 5 tion between the chamber 38 and a passage 48 in the back head leading to a supply reservoir 4| in the forward end-of the back head.

The valve mechanism, constructed in accordance with the practice of the invention, com- 10 prises avalve chest 42 consisting of an outervring member 43 and a plug 44 extending through the ring member 43 and being recessed to provide an annular valve chamber 45 around the plug r 44. The plug 44 carries a flange 46 at its rear 1a end to serve as a seat for the ratchet ring 32 and the rifle bar head 33 and seats upon the rear end of the ring member 43.

The forward end of the plug terminates at the rear end of the piston chamber 22 and may 20 be press-fitted, or otherwise secured, to an annular plate 41 encircling the plug 44 and cooperating therewith to form a closure for the rearward end of the piston'chamber. The plate 41 serves, moreover, as a seat for the front end of 25 the ring member 43 and i provided with a series of inlet ports 48 that afford communication between the rear end of the piston chamber 22 and an annular groove 49 in the rearward end of the annular plate 41 and opening into the front end of the valve chamber 45. Preferably, the inlet ports 48 are so located that their inner portions lie in the same longitudinal plane as the outer portion of the valve chamber 45.

Encircling the rearward end of the valve chamber 45, into which it opens, is an annular groove 50 from which leads an inlet-passage 5| to the front end of the piston chamber.

In the form of the invention illustrated, the pressure fluid is conveyed to the valve chamber 45 by supply passages 52 leading from the supply reservoir 4| through the ratchet ring 32, the flange 46 and into the plug 44. Communication is afiorded between the supply passages 52 and 45 the valve chamber bytwo groups of ports 53 and 54 which are arranged in circular fashion and spaced along the length of the portions of the supply passages 52 lying in the transverse plane of the valve chamber. 50

The ports 53 and 54 are inclined with respect to the axis of the rock drill. Those designated 53, are inclined-towards the rearward extremity of the valve chamber and the ports 54, on the other hand, .areinclinedtowards the front end 55 I of the valve chamber 45.v Annular grooves 55 are preferably formed in the periphery of the plug 44. The grooves 55 communicate with the outlet ends of the ports 53 and 54 and extend to the ends of the valve chamber so clearances will exist between the plug 44 and the inner end surfaces of the valve in all positions of the valve.

The element serving to effect the distribution of pressure fluid from the supply'passages 52 to the inlet passages 48 and is in the form of a ring-shaped valve 56 reciprocable in the valve chamber 45 and having, in the present instance, a smooth unbroken outer surface 51 slidable on a similar surface 58 in the ring member 43. The valve is additionally guided by an internal surface 59 on its inner surface slidable on the peripheral portion 60 of the plug lying between the outlet ends of the ports 53 and 54.,

In the inner surface of the valve 56 are a pair of'annular grooves GI .and 62 which are in constant communication with the ports 53' and 54, respectively. The inner ends of the grooves 6| and 62 are bounded bythe raised portion of the valve carrying the guiding surface 59, and at the outer ends of the grooves are shoulders-63 which are so located that the pressure fluid issuing from the ports 53 and 54 will impinge thereagainst and serve to throw the valve 56 to its limiting positions.

These limiting positions are determined by valve seats 64 and 65 located respectively at the.

rearward and front ends of the valve chamber 45. The valve seat 64 is'of less width than the ad- J'acent portion or end of the valve so that the outer portion of the rear end of the valve will also be constantly exposed to whatever pressure may exist in the front end of the piston chamber 22.

The entire rearward end of the valve constitutes a holding area 66 which is exposed to the pressure fluid flowing from the supply passages across the rearward end of the valve to the inlet passage 5| for holding the valveforwardly during the charging of the front end of the piston chamber. Similarly, the front end of the valve serves as a holding area 61 against which pressure fluid flowing to the rear end of the piston chamber acts for holding the valve 56 rearwardly against the seat .64 during the charging of the rear end of the piston chamber.

The operation of. the device is as follows: With the valve 56' and the piston 23 in the rearmost limiting positions, as illustrated in Figure 1, pressure fluid flows from the ports- 54 into the groove 62 and the adjacent groove 55,,

thence across the holding area 61 through the groove 49 and the'inlet ports 48 into the rear end of the piston chamber to drive the piston 23'forwardly on its working stroke. During this movement of the piston, and after the exhaust port 24 has been closed thereby, the air. in they will drop as will also that acting against the front holding surface 61 of the valve. The compression then acting against the rear endfof the valve together with the pressure. fluid issuing from the ports against the front shoulder 63 will immediately throw the valve forwardly against the seating surface 65 and cutoff the admission of pressure fluid to the rear end of the piston chamber.

In the new position of the valve, pressure fluid flows from the ports 53 into the groove 6| and the adjacent groove 55, thence across the holding surface 66 and through the inlet port 5| to the front end of the piston chamber for return ing the piston 23. After the piston again covers the exhaust port 24 the .air in the rear end of the piston chamber will be compressed and act against the exposed portions of the holding surface 61 lying in the longitudinal planes of the inlet ports 48. The valve 56 will remain in the foremost limiting position until the front end of the piston uncovers the exhaust port 24 at which time there will be an abrupt drop in pressure in the front end of the piston chamber and rearwardly of the holding surface 66. The compression acting against the front end of the valve and the force of the pressure fluid streams striking the rear shoulders 63 will then again shift the valve rearwardly to its initial position.

In the form of the invention illustrated in Figure 3, the valve designated 16 is provided at the forward and rearward ends of its inner surface with groups of annular shoulders H and 12, and in the plug. 44 are front and rear annular'slotsl3 and 14 which are inclined, respectively, toward the front and rear ends of the valve chamber 45. The innermost portions of the slots 13 and 14 communicate with the supply passages 52 and the outermost portions of the slots communicate with the annular grooves 55 in the periphery of the plug 44 so that there is a constant flow of pressure fluid from supply intothe grooves 55 and, therefore, against the shoulders 12.

The operation of this form of the invention is similar to that of the previously described form of the valve butdiffers only therefrom in the respect that during the movement of the valve the shoulders II and 12 move successively into direct line with the-pressure fluid streams issuing from the slots 'I3'and 14 to assure a positive and forceful movement of the valve.

Iclairn: f

1. In a fluid actuated rock drill, the combination of a casing having a piston chamberand a piston therein, an exhaust port for the piston chamber, a valve chest comprising inner and outer members defining an annular space'therebetween forming a valve chamber, inletpassages leading from the valve chamber tothe piston chamber, avalve in 'the valve chamber to control the distribution ofpressure fluid to the inlet passages and having internal surfaces to cooperate with one of the members to define channels for conveying pressure fluid to the inlet passages, passages .in one of the members for introducing pressure fluid from supply into the channels, and shoulderson the valve subjected to the pressure fluid issuing from the last mentioned passagesfor throwing the valve- 2. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve inthe valve chamber having internal annular grooves,

3. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber having internal annular rooves for conveying pressure fluid to the inlet passages, passages in the valve chest affording constant communication between the annular grooves and pressure fluid supply, and shoulders on the valve subjected to pressure fluid issuing from the last mentioned passages for throwing the valve.

4. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber having internal annular grooves for conveying pressure fluid to the inlet passages, passages in the valve chest opening into the annular grooves, shoulders on the valve forming bounding surfaces for the annular grooves and being subjected to the pressure fluid issuing from the last mentioned passages for throwing the valve, and holding surfaces on the valve subjected to the pressure fluid flowing to the inlet passages for holding the valve in the limiting positions.

5. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber cooperating with the valve chest to define annular channels within the valve for conveying pressure fluid to the inlet passages,

passages in the valve chest inclined toward the extremities of the valve chamber for conveying pressure fluid from supply to the annular channels, and shoulders on the valve subjected to the pressure fluid issuing from the last mentioned passages for throwing the valve.

6. In a fluid actuated rock 'drill, the combination of .a casin having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber having annular grooves in its inner surface for conveying pressure fluid to the inlet passages, supply passages in the valve chest opening into the annular grooves and being inclinedtoward the extremities of the valve chamber, and shoulders on the inner surface of the valve subjected to the pressure fluid issuing from the supply passages for throwing the valve.

7. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust port for the piston chamber, a valve chest having an annular valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber having annular grooves in its innor surface for conveying pressure fluid to the inlet passages, supply passages in the valve chest opening into the annular grooves, shoulders on the valve subjected to the pressure fluid issuing from the supply passages for throwing the valve, surfaces on the ends of the valve subjected to the pressure fluid flowing to the inlet passages for holding the valve in the limiting positions, and portions of the said surfaces subjected to compression from the piston chamber to assist in throwing the valve.

ALBERT R. MACK. 

